This invention relates to an apparatus for determining the presence of foreign bodies such as metal parts, wires or the like within or between fiber tufts, particularly tufts of cotton and/or chemical fibers.
In practice, undesired foreign bodies such as metal parts, metal wires and the like can be found within or between cotton or chemical fiber tufts. Such foreign bodies adversely affect the processing of the fiber, particularly in the manufacture of high-grade yarns. During processing in cleaning and spinning installations, the foreign bodies gain access to the processing machines resulting in damages of the cylinder clothings or causing burns. The foreign bodies may be metal straps or wires with which the compressed fiber bales were tied. Frequently, the foreign bodies are found within the compressed fiber bales. Such pressed-in foreign bodies often reach through a plurality of layers (zones) so that attendants have to dig into the fiber bales manually until the entire foreign body may be lifted out. Such a procedure is very time-consuming and adversely affects a continuous processing.
In the processing of cotton, artificial fibers and other similar fiber material, it is a frequent occurrence that machine components are damaged by impurities, particularly metal objects. Such damages are particularly disadvantageous at locations where processing is performed by clothed cylinders or rollers, which may be found in cards with flats and sawtooth cleaners, etc. In machines of this type the introduction of a metal object leads to the destruction of the clothing, an interruption in the production and high repair costs.